<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        *{
            padding: 0;
            margin: 0;
        }
        .box{
            width: 100%;
            height: 130px;
            position: relative;
        }
        #prize{
            width: 80%;
            height: 180px;
            font-size: 30px;
            text-align: center;
            color: rgb(255, 0, 0);
            line-height: 180px;
            position: absolute;
            z-index: 1;
        }
        #cavsElem{
            position: absolute;
            z-index: 2;
        }
        
    </style>
   
</head>
<body>
    <div class="box">
        <canvas id="cavsElem"></canvas>
        <div id="prize">Thank You</div>
    </div>
    <script>
       var  canvas = document.getElementById('cavsElem');
            canvas.width=window.innerWidth;
            canvas.height=150;
       
       var  context= canvas.getContext('2d');
            context.fillStyle='#9A9A9A';
            context.fillRect(0,0,window.innerWidth,150);
            canvas.addEventListener("touchstart",function(e){
            canvas.addEventListener("touchmove",function(e){
            context.clearRect(e.touches[0].clientX,e.touches[0].clientY,30,30);
        })
    })
       var arr = ["签名照","陈立农同款卫衣联名","一千元","谢谢惠顾"];
       var i=Math.floor(Math.random()*arr.length);
       var mydiv=document.getElementById("prize");
       mydiv.innerHTML=arr[i];



    </script>
</body>
</html>